149 lines
3.5 KiB
C
149 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Raspberry Pi voltage sensor driver
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*
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* Based on firmware/raspberrypi.c by Noralf Trønnes
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*
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* Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se.com>
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*/
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#include <linux/device.h>
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#include <linux/devm-helpers.h>
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#include <linux/err.h>
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#include <linux/hwmon.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/workqueue.h>
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#include <soc/bcm2835/raspberrypi-firmware.h>
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#define UNDERVOLTAGE_STICKY_BIT BIT(16)
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struct rpi_hwmon_data {
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struct device *hwmon_dev;
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struct rpi_firmware *fw;
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u32 last_throttled;
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struct delayed_work get_values_poll_work;
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};
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static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
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{
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u32 new_uv, old_uv, value;
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int ret;
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/* Request firmware to clear sticky bits */
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value = 0xffff;
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ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_THROTTLED,
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&value, sizeof(value));
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if (ret) {
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dev_err_once(data->hwmon_dev, "Failed to get throttled (%d)\n",
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ret);
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return;
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}
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new_uv = value & UNDERVOLTAGE_STICKY_BIT;
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old_uv = data->last_throttled & UNDERVOLTAGE_STICKY_BIT;
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data->last_throttled = value;
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if (new_uv == old_uv)
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return;
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if (new_uv)
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dev_crit(data->hwmon_dev, "Undervoltage detected!\n");
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else
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dev_info(data->hwmon_dev, "Voltage normalised\n");
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hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
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}
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static void get_values_poll(struct work_struct *work)
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{
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struct rpi_hwmon_data *data;
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data = container_of(work, struct rpi_hwmon_data,
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get_values_poll_work.work);
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rpi_firmware_get_throttled(data);
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/*
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* We can't run faster than the sticky shift (100ms) since we get
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* flipping in the sticky bits that are cleared.
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*/
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schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
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}
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static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
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u32 attr, int channel, long *val)
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{
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struct rpi_hwmon_data *data = dev_get_drvdata(dev);
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*val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
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return 0;
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}
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static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
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u32 attr, int channel)
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{
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return 0444;
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}
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static const struct hwmon_channel_info *rpi_info[] = {
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HWMON_CHANNEL_INFO(in,
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HWMON_I_LCRIT_ALARM),
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NULL
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};
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static const struct hwmon_ops rpi_hwmon_ops = {
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.is_visible = rpi_is_visible,
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.read = rpi_read,
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};
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static const struct hwmon_chip_info rpi_chip_info = {
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.ops = &rpi_hwmon_ops,
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.info = rpi_info,
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};
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static int rpi_hwmon_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct rpi_hwmon_data *data;
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int ret;
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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/* Parent driver assure that firmware is correct */
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data->fw = dev_get_drvdata(dev->parent);
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data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
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data,
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&rpi_chip_info,
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NULL);
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if (IS_ERR(data->hwmon_dev))
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return PTR_ERR(data->hwmon_dev);
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ret = devm_delayed_work_autocancel(dev, &data->get_values_poll_work,
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get_values_poll);
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if (ret)
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return ret;
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platform_set_drvdata(pdev, data);
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schedule_delayed_work(&data->get_values_poll_work, 2 * HZ);
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return 0;
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}
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static struct platform_driver rpi_hwmon_driver = {
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.probe = rpi_hwmon_probe,
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.driver = {
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.name = "raspberrypi-hwmon",
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},
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};
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module_platform_driver(rpi_hwmon_driver);
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MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
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MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
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MODULE_LICENSE("GPL v2");
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MODULE_ALIAS("platform:raspberrypi-hwmon");
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